Hair dryer

ABSTRACT

A hair dryer has a casing, a switch, a blower, a mounting cylinder and a heating coil. The casing is hollow and has at least one air inlet and an air outlet. The switch is mounted on the casing. The blower is mounted in the casing and connects to the switch. The mounting cylinder is heat-resistant and insulating and is mounted in the casing. The heating coil having at least one first segment and at least one second segment is mounted around the mounting cylinder, wherein the two segments are wrapped in different directions. When the hair dryer is activated, magnetic fields resulted from the electrified heating coil and the motor tend to partially cancel each other. Therefore, the electromagnetic energy near the air outlet is reduced.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hair dryer, and more particularly to a hand-held hair dryer that efficiently reduces the emission of the electromagnetic radiation near the air outlet by interfering the electromagnetic radiation emitted from heating coils with the electromagnetic radiation emitted from a motor.

2. Description of Related Art

With reference to FIGS. 4 and 5, a typical hair dryer has a casing (70) with a barrel, an air outlet, a blower driven by a motor (72) and a heating coil (74). When operating, the blower blows and causes airflow to pass through the electrified heating coil. The airflow is heated by the heating coil (74) and then passes through the air outlet to blow a user's hair. The typical heating coil (74) is wrapped around a mounting cylinder being mounted securely in the casing (70) in a clockwise or counterclockwise direction. In accordance with Ampere's circuital law, the spiral heat coil (74) will generate electromagnetic radiation (A) along an axis direction of the barrel. The motor (72), either a DC motor or an AC motor, generates electromagnetic radiation (B) along another direction perpendicular to the axis direction of the barrel. Because the electromagnetic radiation respectively resulted from the heating coil (74) and the motor (72) emit in different directions, the electromagnetic radiation near the air outlet of the hair dryer is harmful to human.

To overcome the shortcoming, the present invention provides a hair dryer to mitigate or obviate the aforementioned problem.

SUMMARY OF THE INVENTION

The main objective of the invention is to provide a hand-held hair dryer that efficiently reduces the emission of the electromagnetic radiation deriving from the heating coils when operating and is safe for use.

A hair dryer has a casing, a switch, a blower, a mounting cylinder and a heating coil. The casing is hollow and has at least one air inlet and an air outlet. The switch is mounted on the casing. The blower is mounted in the casing and connects to the switch. The mounting cylinder is heat-resistant and insulating and is mounted in the casing. The heating coil having at least one first segment and at least one second segment is mounted around the mounting cylinder, wherein the two segments are wrapped in different directions. When the hair dryer is activated, magnetic fields resulted from the electrified heating coil and the motor tend to partially cancel each other. Therefore, the electromagnetic energy near the air outlet is reduced.

Other objectives, advantages and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view in partial section of a hair dryer in accordance with the present invention;

FIG. 2 is an enlarged side view of a heating coil being wrapped around a mounting cylinder of the hair dryer in accordance with the present invention;

FIG. 3 is an enlarged side view of a heating coil of a second embodiment being wrapped around a mounting cylinder of the hair dryer in accordance with the present invention;

FIG. 4 is a side view in partial section of a hair dryer in accordance with prior art; and

FIG. 5 is an enlarged side view of a heating coil being wrapped around a mounting cylinder of the hair dryer in accordance with the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, a hair dryer in accordance with the present invention comprises a casing (10), a switch (20), a blower, a mounting cylinder (50) and a heating coil (60).

The casing (10) is hollow and has a handgrip, a barrel (12), a cavity, at least one air inlet (11) and an air outlet (13). The handgrip is formed on the casing (10). The barrel (12) is formed on the casing (10) and has a passage defined in the barrel (12) along an axis direction. The cavity is defined in the casing (10) and communicates with the passage. The at least one air inlet (11) and the air outlet (13) are defined in the casing (10) and communicate with the cavity.

The switch (20) is mounted on the handgrip and may selectively slide to different positions to control the temperature of the airflow generated by the hair dryer.

The blower is mounted in the cavity of the casing (10) and has a motor (30) and a fan (40). The motor (30) is mounted in the cavity in the casing (10) and connects to the switch (20), so the motor (30) can be turned on or off through the switch (20). The fan (40) is connected rotatably to and driven by the motor (30) and is adjacent to the at least one air inlet (11).

The mounting cylinder (50) is heat-resistant and insulating, is mounted securely in the passage in the barrel (12) and has an inside end adjacent to the at least one air inlet (11) and an outside end adjacent to the air outlet (13).

The heating coil (60) is wrapped spirally around the mounting cylinder (50), may have at least one first coil segment (61) wrapped in a clockwise direction and at least one second coil segment (62) formed integrally with the first coil segment (61) and wrapped in a counterclockwise direction.

When turning on the hair dryer to activate the motor (30), a magnetic field (31) is generated around the motor (30). When the hair dryer is turned on, the heating coil (60) is electrified with a current identified by arrows of broken lines on FIG. 2 and the first and second coil segments (61)(62) generate other magnetic fields (64) that tend to cancel the magnetic filed of the motor (30) or being guided to the motor (30) somewhat. Therefore, the intensity of the aggregate magnetic field is smaller than a conventional heating element, and electromagnetic energy near the air outlet (13) is effectively reduced.

With reference to FIG. 3, the heating coil (60) in accordance with a second embodiment of the present invention comprises multiple separate coil segments (61A,62A,61B). Each of the coil segments (60G, 60H) has two contacts. While the first coil segment (61A) and the third coil segment (61B) are wrapped spirally around the mounting cylinder (50) in a clockwise direction, the second coil segment (62A) is wrapped spirally around the mounting cylinder (50) in a counterclockwise direction. When the coil segments (61A,62A,61B) are electrified with a current identified by arrows of broken lines, the multiple separate coil segments (61A,62A,61B) generate other magnetic fields (64) that tend to cancel the magnetic filed of the motor (30).

Even though numerous characteristics and advantages of the present invention have been set forth in the foregoing description, together with details of the structure and function of the invention, the disclosure is illustrative only. Changes may be made in the details, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed. 

1. A hair dryer comprising: a casing being hollow and having a barrel formed on the casing and having a passage defined in the barrel, a cavity defined in the casing and communicating with the passage, at least one air inlet and an air outlet defined in the casing and communicating with the cavity; a switch mounted on the casing; a blower mounted in the cavity in the casing and having a motor mounted in the cavity and connecting to the switch and a fan connected rotatably to the motor; and a mounting cylinder being heat-resistant and insulating and mounted in the passage; and a heating coil wrapped spirally around the mounting cylinder and having at least one first coil segment wrapped in a clockwise direction; and at least one second coil segment wrapped in a counterclockwise direction; when the motor and the heating coil are electrified to generate magnetic fields respectively, the magnetic fields of the heating coil and the motor partially cancel each other to reduce electromagnetic energy near the air outlet.
 2. The hair dryer as claimed in claim 1, wherein the at least one second coil segment is formed integrally with the first coil segment and connected in series.
 3. The hair dryer as claimed in claim 1, wherein the at least one first coil segment is separated from the at least one second coil segment. 